Re: Support of removable MTD devices and other advanced features (follow-up from lkml)

[Artem Bityutskiy <dedekind@infradead.org>]

Hi,

I do not know much about SmartMedia and so on, so I cannot really
comment. I mail more because I am afraid your mail will not be answered.
Probably you should keep CCing LKML, not sure.

On Tue, 2008-05-20 at 06:59 -0700, Alex Dubov wrote:
> And third, architectural switch I'm proposing should not require modification
> to low level chip drivers or higher level functionality of UBI kind. They can
> be glued together with relative ease (callback architecture is quite flexible).
> My target is device management and FTL drivers.
> 
> Therefore, I propose (and intend to implement) a new architecture for MTD core,
> modeled after the block device API. The "alpha" version of it is here:
> 
> http://gentoo-wiki.com/User:Oakad/mtd_proposal

I've briefly read through this. I think it is nice having an
asynchronous interface based on requests. Probably UBI/UBIFS would
benefit from it as well. Just few thoughts:

1. You will probably need to solve the horrible MTD problem - it does
not support devices larger than 4GiB because it uses absolute 32-bit
offsets.
2. You will need to make MTD sysfs-aware.
3. Removable devices support is a separate task as well.
4. IMO you should preserve the low-level flash access interface and the
request-based infrastructure should yous it as the back-end. Is this
possible? Or my understanding of smartmedia is incorrect? I thought it
is accessible as bare NAND and you have to support its FTL in software. 

Probably there are other tasks. I think you should work on these smaller
tasks separately and make them go in one by one, instead of trying to
put all together.

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)